RESUMO
The interaction of the T-cell receptor (TCR) with peptide antigen plus major histocompatibility complex (MHC) protein requires both alpha and beta chains of the TCR. The "superantigens" are a group of molecules that are recognized in association with MHC class II but that do not appear to conform to this pattern. Superantigens are defined as such because they cause the activation or thymic deletion of many or all T cells bearing specific TCR beta-chain variable region (V beta) elements. The strong association of particular V beta S with T-cell responses to superantigens suggests that their interaction with the TCR is fundamentally different from that of most antigens. We have directly investigated the involvement of the beta chain in recognition of a superantigen by using a secreted, truncated TCR beta chain and the bacterial superantigen staphylococcal enterotoxin A complexed to cell-surface MHC class II. We demonstrate that this interaction is specific for the enterotoxin and is dependent on MHC class II expression by the cell. The reaction can be inhibited by antibodies against the three components of the reaction: V beta, enterotoxin, and class II. This shows that the TCR beta chain is sufficient to mediate the interaction with a superantigen-class II complex. The TCR alpha chain and co-receptors such as CD4 are not required.
Assuntos
Antígenos de Histocompatibilidade Classe II/imunologia , Receptores de Antígenos de Linfócitos T/imunologia , Anticorpos Monoclonais , Complexo Antígeno-Anticorpo , Linfoma de Burkitt , Linhagem Celular , Enterotoxinas/imunologia , Ensaio de Imunoadsorção Enzimática , Citometria de Fluxo , Humanos , Região Variável de Imunoglobulina/imunologia , Substâncias Macromoleculares , Ligação Proteica , Staphylococcus aureus/imunologia , Linfócitos T Auxiliares-Indutores/imunologiaRESUMO
The last few years have seen an enormous jump in our knowledge and understanding of T-cell activation by superantigens. Clearly, a great number of infectious and parasitic organisms utilize superantigens as part of a strategy to evade the immune response of their host. The ability to modulate superantigen effects will give us new means to fight infections, and the knowledge of T-cell activation that we have gained from study of superantigens will, in turn, allow us to modulate the immune system in new ways.